Boron trifluoride etherate, strictly boron trifluoride diethyl etherate, or boron trifluoride–ether complex, is the chemical compound with the formula BF₃O(C₂H₅)₂, often abbreviated BF₃OEt₂. It is a colorless liquid, although older samples can appear brown. The compound is used as a source of boron trifluoride in many chemical reactions that require a Lewis acid.^[1] The compound features tetrahedral boron coordinated to a diethylether ligand.^[2] Many analogues are known, including the methanol complex.

Quick Facts Names, Identifiers ...

Boron trifluoride etherate

Names
Other names Boron Trifluoride Ethyl Ether Boron Trifluoride Diethyl Etherate
Identifiers
CAS Number	109-63-7
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL1710835
ChemSpider	17983029
ECHA InfoCard	100.003.355
PubChem CID	517922
UNII	422VHH19IT
UN number	2604
CompTox Dashboard (EPA)	DTXSID90985377 DTXSID40861733, DTXSID90985377
InChI InChI=1S/C4H10O.BF3/c1-3-5-4-2;2-1(3)4/h3-4H2,1-2H3; Key: KZMGYPLQYOPHEL-UHFFFAOYSA-N
SMILES B(F)(F)F.CCOCC
Properties
Chemical formula	C4H10BF3O
Molar mass	141.93 g·mol−1
Appearance	colorless liquid
Density	1.15 g cm3
Melting point	−58 °C (−72 °F; 215 K)
Boiling point	126 °C (259 °F; 399 K)
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Flammable, Reacts with water, Corrosive
GHS labelling:
Pictograms
Signal word	Danger
NFPA 704 (fire diamond)	3 2 2 W
Flash point	58.5 °C (137.3 °F; 331.6 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Close

Boron trifluoride etherate serves as a source of boron trifluoride according to the equilibrium:

BF₃OEt₂ ${\displaystyle {\ce {<=>>}}}$ BF₃ + OEt₂

The BF₃ binds to even weak Lewis bases, inducing reactions of the resulting adducts with nucleophiles.^[1]